Action device for electric musical instrument

ABSTRACT

An action device for an electric musical instrument having a frame, an electrostatic type pickup mounted on the frame, a center rail fixed to the frame, a flange attached thereto, a hammer pivoted to the frame, and a hammer rail fixed to the center rail. In this case, the device is formed in such a manner that the electric charge stored on the hammer is grounded.

I Umted States Patent 1111 3,621,105

[72] Inventor NaokichlTakamatsu [56] References Cited 1 N g g ga m Japan UNITED STATES PATENTS P" Re.2l,225 10/1939 Miessneretal 84/l.l6 x [22] Wed (611970 215 977 5/1879 1166616111.; 84/452 x [45] Patented Nov. 16, 1971 239'670 4/1881 N d I y pruck et al. 84/452 X [731 Cdmnb Kabushikikmh' 1 411 820 4/1922 Waggett 84/452 g f Cdumb" 2:001:392 5/1935 Miessner 84/1.l6 2,071,649 2/1937 Mlcssneretal 84/].16 x [321 101197) 2.535,;141 12/1950 Zcckman 84/].16 x f 3.360663 12/1967 Crewe ct di 310/5 [3 1 5/2 359 3,501,653 3/1970 Bailey 310/5 x Primary ExaminerD. X1 Sliney Assistant Examiner- Ulysses Weldon Allorney-Hill, Sherman. Meroni. Gross & Simpson [54] ACTION DEVICE FOR ELECTRIC MUSICAL i g gf grgg g Figs. ABSTRACT: An action device for an electric musical instrument having a frame, an electrostatic type pickup mounted on [52] US. Cl 1. 84/].16, the frame, a center rail fixed to the frame, a flange attached 84/106, 84H 14 thereto, a hammer pivoted to the frame, and a hammer rail [51] lnt.Cl 1 Gl0h 3/00 fixed to the center rail. In this case, the device is formed in [50] Field of Search 84/1 .01, such a manner that the electric charge stored on the hammer is grounded.

PAIENTEBIIW 16 I971 SHEET 2 [IF 2 lOb INVI-IN'I I W In ACTION DEVICE FOR ELECTRIC MUSICAL INSTRUMENT BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an action device for an electric musical instrument such as an electric piano having an electrostatictype pickup in which variation of electrostatic capacity between a mechanical vibrator and a fixed electrode is converted to an electric signal and is made a sound through a speaker.

2. Description of the Prior Art In an electric musical instrument a vibrator thereof is percussed by a hammer to be vibrated. In the prior art instrument, the hammer is made of plastics and its surface to be contacted with the vibrator is coated with felt, rubber or the like. In general, the plastic, felt, rubber or the like material is apt to be charged with static electricity, so that the electrostatic charge is stored in the hammer in the vicinity of the surface thereof.

With an electrostatic type musical instrument having provided with such a hammer, when the hammer percusses a vibrator of the musical instrument, the electrostatic charge stored in the hammer is transferred to the vibrator. As a result, the electrostatic capacity between the vibrator and the fixed electrode of the electric musical instrument is changed to make a noise.

SUMMARY OF THE INVENTION The main object of the present invention is to provide an electrostatic musical instrument which positively avoids the variation of an electrostatic capacity between a vibrator and an electrode due to electric charge transferred from a hammer to thereby prevent occurrence of noise.

Other objects, features and advantages of the present invention will be clearly understood by the description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side view, partially in cross section, of an action device for an electric musical instrument according to the present invention; and

FIG. 2 is an enlarged plane view for illustrating one part of the device depicted in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the FIGS. reference numeral I indicates a frame made of electrically conductive metal, for example; 2, a fixed electrode and 4, a fitting base made of electrically conductive material one end of which is attached to one end of the frame 1 by a screw 3. One end of the fixed electrode 2 is fixed to the free end of the fitting base 4 by means of a screw 10a. Reference numerals 5 and 6 represent washers which are respectively made of electrically insulating material for insulating the fitting base 4 from the frame 1 and 7a washer. Reference numeral 8 designates an electrostatic capacity detecting member which consists of a pair of electrode plates 8a and 8b and formed at the free end of the fixed electrode 2 and 9 a vibrator, one end of which is fixed to the frame 1 at the other end thereof by means of a bolt 14 and a washer l3 and the other end or free end of which is positioned between the electrode plates 8a and 81; without being contacted therewith. Reference numeral 10b indicates an adjusting screw for adjusting the fixed electrode 2 with respect to the fitting base 4 or adjusting the position of the electrode plates 8a and 8b, 11 a screw provided in association with the fixed electrode 2 for adjusting the distance and position of the electrostatic capacity detecting member 8, namely the distance between the electrode plates 8a and 8b and 12 a weight formed of solder, lead etc. and mounted on the free end portion of the vibrator 9 for adjusting the vibration frequency of the vibrator 9. Reference numeral 13 is a washer. Reference numeral 14 is a bolt for attaching the vibrator 9 to the frame I. The frame 1 has provided therewith :1 lug 15 made of conductive material or same material as that of the frame to which one end of u fitting member I6 made of conductive material is fixed by means of, for example, a screw 16a. To the other end of the fitting member 16 a center rail 17 made of conductive material is attached by, for example, a screw 16b. The center rail I7 has attached thereto a flange 18 made of plastic material and with its surface being coated with a thin film made of conductive material and a hammer rail fitting member I9 made of metal by means of, for example, screws 18a and I9a respectively. A hammer 20 made of plastic material is pivotally attached to the flange 18. In this case the surface of the hammer 20 is made to be conductive by, for example, coating a conductive film on the surface. Reference numeral 21 indicates a hammer felt which is fixed to the hammer 20 on the portion striking the vibrator 9. The thickness of the hammer felt 21 is selected to be very thin, about I mm., 22 a hammer rail supported by the hammer rail fitting member 19 on its free end portion, 23 a hammer rail .felt which is mounted on the hammer rail 22 on the portion receiving the end of the hammer 20 opposite to that with the hammer felt 21, 24 a jack which may hit the hammer 20 at the portion near the pivoted point, 25 a felt coated on the hammer 20 in the vicinity of its pivot and 26 a cloth adhered to the hammer 20 on the part to be pushed by the jack 24. Reference numeral 27 is a spring made of conductive material which is stretched between the flange l8 and the hammer 20 and normally supports the hammer 20.

With such an arrangement when an AC voltage of about 200 volts is applied to the fixed electrode 2, the frame I is grounded and the vibrator 9 is percussed by the hammer 20, the vibrator 9 vibrates at a predetermined frequency. As a result of this, the electrostatic capacity established between the electrostatic capacity detecting member 8 and the vibrator 9 is varied due to the displacement of the free end of the vibrator 9 between the opposed electrode plates 8a and 8b and the variation of the electrostatic capacity is detected as a corresponding electric signal such, for example, as current or voltage. The means for detecting the electrostatic capacity variation and converting the variation into a corresponding electric signal is not shown and explained in the specification for the reason that this means is well known in the art.

In this case, according to the present invention, the electric charge stored on the hammer 20 is grounded through the circuit of the hammer 20, the flange 18, the center rail 17, the fitting member 16, the lug l5 and the frame I, so that any electric charge is not stored on the hammer 20. Accordingly, no electric charge is transferred to the vibrator 9 when the vibrator 9 is percussed by the hammer 20, which will mean that no noise is produced.

In the event that electric charge is produced and stored in the hammer felt 21, since the hammer felt 21 is very thin in the present invention as explained above, the electric charge stored on the hammer felt 21 may be grounded through the circuit same to that explained above. Accordingly, the charge may have no affect upon the electrostatic capacity between the electrostatic capacity detecting member 8 and the vibrator 9 in practice.

In order to make the hammer 20 and the flange l8 conductive, they may be made of electrically conductive material or material containing therein powders of metal or carbon in addition to coat the surfaces of them with metal or carbon layer.

In the case where only the hammer 20 is made to be conductive, the spring 27 may be grounded to transfer the charge stored on the hammer to the earth.

If the hammer and the flange are made of conductive material such, for example, as metal, it is prevented that charge may be produced on the hammer.

I claim as my invention:

1. An action device for an electric musical instrument comprising a frame, an electrostatic-type pickup attached to said frame, a center rail fixed to said frame, a flange attached to said center rail, a hammer pivotally attached to said flange, a hammer rail fixed to said center rail, and grounding means attached to said hammer.

2. An action device as claimed in claim 1 wherein said frame is made of conductive material and said grounding means consists of members which make the surfaces of said center rail, flange and hammer electrically conductive together to ground the electric charge stored on said hammer.

3. An action device as claimed in claim 1 wherein a spring is stretched between said flange and hammer, said spring being grounded and said means consists of a member which makes the surface of said hammer electrically conductive.

4. An action device as claimed in claim 2 wherein said flange is made of metal.

5. An action device as claimed in claim 2 wherein said flange is made of nonconductive material the surface of which is coated with a layer made of electrically conductive material.

6. An action device as claimed in claim 2 wherein said flange is made of material which consists of nonconductive material and powders of an electrically conductive material mixed therewith.

7. An action as claimed in claim 3 wherein said hammer is made of metal.

8 An action as claimed in claim 3 wherein said hammer is made nonconductive material the surface of which is coated with a layer made of an electrical conductive material.

9. An action device as claimed in claim 3 wherein said hammer is made of material which consists of nonconductive material and powders of an electrically conductive material mixed therewith.

10. An action device as claimed in claim 2 wherein said hammer is made of metal.

ll. An action device as claimed in claim 2 wherein said hammer is made of nonconductive material the surface of which is coated with a layer made of electrically conductive material.

12. An action device as claimed in claim 2 wherein said hammer is made of material which consists of nonconductive material and powders of an electrically conductive material mixed therewith. 

1. An action device for an electric musical instrument comprising a frame, an electrostatic-type pickup attached to said frame, a center rail fixed to said frame, a flange attached to said center rail, a hammer pivotally attached to said flange, a hammer rail fixed to said center rail, and grounding means attached to said hammer.
 2. An action device as claimed in claim 1 wherein said frame is made of conductive material and said grounding means consists of members which make the surfaces of said center rail, flange and hammer electrically conductive together to ground the electric charge stored on said hammer.
 3. An action device as claimed in claim 1 wherein a spring is stretched between said flange and hammer, said spring being grounded and said means consists of a member which makes the surface of said hammer electrically conductive.
 4. An action device as claimed in claim 2 wherein said flange is made of metal.
 5. An action device as claimed in claim 2 wherein said flange is made of nonconductive material the surface of which is coated with a layer made of electrically conductive material.
 6. An action device as claimed in claim 2 wherein said flange is made of material which consists of nonconductive material and powders of an electrically conductive material mixed therewith.
 7. An action as claimed in claim 3 wherein said hammer is made of metal.
 8. An action as claimed in claim 3 wherein said hammer is made nonconductive material the surface of which is coated with a layer made of an electrical conductive material.
 9. An action device as claimed in claim 3 wherein said hammer is made of material which consists of nonconductive material and powders of an electrically conductive material mixed therewith.
 10. An action device as claimed in claim 2 wherein said hammer is made of metal.
 11. An action device as claimed in claim 2 wherein said hammer is made of nonconductive material the surface of which is coated with a layer made of electrically conductive material.
 12. An action device as claimed in claim 2 wherein said hammer is made of material which consists of nonconductive material and powders of an electrically conductive material mixed therewith. 